hiding extensions

i'm sorry guys, i'm stumped. i've been working at this for the past two days and haven't gotten anywhere.
of course this isn't terribly important either, more of a learning exercise than anything.

so i'm trying to hide extensions, any kind of extensions from the address bar.
basically rewriting say features.php to features/
i think this is like the basic of the basic rewrite rule, so i've tried the following rule in a few variations

RewriteRule ^(.*)/(.*).php$ /$1/ [I]

assuming that it means rewrite any php files under any directory to name/
i have yet to get it to work with anything in wwwroot or a virtual directory on a different harddrive -_-

please re-read the Readme file and make sure you understand the difference between a rewrite and a redirect.
This key point is explained there. it is essential that you understand it before trying to hide extensions from the browser.